Manufacture of sulphuric acid



MANUFACTURE OF SULPHURIC ACID Filed April 29, 1926 COOLER ABSORBERINVENTOR fiE/V/P/F Mf/PAMM BY 7 6 g ATTORNEY Patented Sept. 17, 192%satire stares PATENT OFFICE HENRY F. MERRIAM, OF WEST OBANGE, NEWJERSEY, ASSTGNOR TO GENERAL CHEMICAL COMPANY, OF NEW YORK, N. Y., ACORPORATION OF NEW YORK MANUFACTURE OF SULPHURIG ACID Application filedApril 29, 1926. Serial No. 105,344.

My present invention relates to the manufacture of sulphuric acid andparticularly to the contact process for the production of such acid bythe catalytic action of certain substances on a gaseous mixturecontaining sulphur dioxide and oxygen. The invention has for its objectthe provision of a system characterized by decreased corrosion of theequipment and marked economies in operation, as more fully pointed outhereinafter. The importance of purifying the gases employed in themanufacture of sulphuric acid has been realized for some time and'various attempts have been made to deprive the gases of certainimpurities before bringing them in contact with the catalytic agent.More particularly the removal of moisture from the air or otheroxygen-com taining gas by means of sulphuric acid as a drying agent hasbeen resorted to heretofore. The older practice employed for thispurpose consisted in drying the burner gases after a scrubbing andfiltering treatment and then passing such gases through a compressor todeliver them to the contact chambers with the proper excess of oxygen toenable the sulphuric anhydride to be formed. In the more recent practicein which sulphur dioxide gases are produced from Louisiana brimstone andpassed to the contact chambers without a cold purification treatment,the air used for combustion is dried by means of sulphuric acid and thenpassed through a compressor to deliver it to a burner in which sulphurdioxide gases are produced, said gases being then passed on to thecontact apparatus. The difliculty with both practices is that the gases,in their passage through the drier, will inevitably pick up some of thedrying agent and carry it into the compressor or blower, and since thelatter is made of material attacked by sulphuric acid,'the corrosiveaction of the 4 sulphuric acid onthe compressor will in time impair verymaterially the eificiency of such apparatus. Particularly when thecompressor was of the rotary or blower type, corrosion resulted in anincrease of clearances which finally became so great as to requirereplacement of the blowers or at least of their main portions.

Other possible places to put the blower or compressor are following theabsorber, or between the burner and converter. The difliculty with thefirst mentioned position is the same as that existing when the blower isplaced following the drier,.namely corrosion of the blower resultingfrom sulphuric acid carried over from the absorber. The second mentionedposition has the obviously great disadvantage of requiring the blower tohandle exceedingly hot sulphurous gases; not only necessitating a blowerof greatly increased capacity to handle the greater volume of gas due toits increased temperature, but also imposing severe operatingconditions.

In order to avoid these difliculties, I have devised the present processand apparatus,

according to which the air is compressed before its admissionto thedrier. Thus, the acid picked up by the gases during their passagethrough the drier cannot reach the blower and the latter remains inserviceable condition for a practically indefinite length of time. Anysulphuric acid picked up by the gases during their passage through thedrier is conducted at once to the burner where such acid is not liableto produce any detrimental effects. The blower or compressor whenoperating in accordance with my invention is running at a temperaturelower than that obtaining at any other point in the system, thuspermitting a blower of minimum size to be used and reducing operatingcosts.

In the accompanying drawing, a plant suitable for the carrying out ofthe present asbestos to remove impurities such as dust and also certainother impurities, for instance oil, which may get into the air withinthe blower from the lubricated bearings of the blower shaft. D indicatesa drier omitted, the outlet of the blower being in that event connecteddirectly with the inlet of the drier. From the outlet of the drier theair or other oxygen-containing gas passes through a conduit F to asulphur burner or combustion chamber G of'any suitable construction. Theoutlet ofthis burner. is connected by a conduit H with a cooler I fromwhich a conduit J leads to a converter K of the type for convertingamixture of sulfur dioxide gas and oxygen intqsulphuric anhydride. Thissulphuric anhydride, with inert gases" if present, then passes through aconduit, L to a cooler M and then through another conduit N to anabsorber 0 from the outlet P of which the resulting liquid, sulphuricacid, is conducted to storage or other place of disposal, the unabsorbedgases escaping at Q.

The air or other oxygen-containing gas is under pressure throughout theprocess from the outlet of the blower A to the final exit Q, of theabsorber. Dust or like 'impurities and also an lubricating oil that theair may have ta en up in the blower are eliminated in the filter B. Assug ested above however, if the air is origin'a y of great purity, thefilter B may be omitted. The compressed air then enters the drier D andis there deprived of its moisture. The dry air then proceeds to theburner Gin which elemental sulphur or brimstone is burned with oxygen toroduce sulfur dioxide gases in any wellown or approved manner itbeingunderstood that an excess of oxygen is present'so thatthe gases passingoutat H contain sulphur dioxide and oxygen in proper proportion fortheir subsequent conversion into sulphuric anhydride "by the catalyticreaction taking place in the converter K, wherein the oxidation of thesulphur to sulphur trioxide is completed. Any

sulphuric acidwhich the gases may pick up during their passage throughthe drier D will pass on directly to theburner G. The reaction occurringin ths part of the apparatus is such that the resence of the smallamount of sulphuric acid in the gases will not be objectionable. It willbe noted .that, contra to the practice hitherto, the sulp uric acid ickeup in the drier is not allowed to reac the blower, and the detrimentalcorrosive efiect of the sulphuric acid on the blower is thus eflicientlyavoided. considerable saving in the repair costs and depreciation iseffected by using thepresent invention. The fact that a positivepressure is employed during the entire treatment is also of considerablevalue in that the volume of gases under treatment is materially re-.oduceds The sulphuric acid employedms a drying agentmay be of 98%concentration or its strength may be only from 60 Be.

to'66 B..

It be appreciated that my invention is of particular value in connectionwith that modification of the contact process previously describedherein in which sulphurous gases are produced from sulfur of theLouisiana type and then passed without material lowering of theirtemperature below the eflfective conversion temperature of S0 to S0, tocontact chambers containing a platinum type of contact material. In thismodification no moisture is introduced into the system, as is done, whenusing the old cold purification treatment of the burner gases, andconsequently the moisture content of the entiresystem is lowered byplacing the drying equipment at the beguming of the system.

It will, of course, be understood that my invention would be applicablewith the same success if any other drying agent having corrosiveproperties should be used instead of sulphuric acid since the genericefiect of preventing corrosion of the compressor parts would still beobtained, and I desire it to be understood that any corrosive agenthaving the property of removing moisture from air or similar gases is tobe considered an equivalent of sulphuric acid for the purpose of dryingand that the appended claims are to be interpreted accordingly.

I claim:

1. Thei improvement in the process of manufacturing sulphuric anhydridewhich consists in initially compressing air withdrawn at atmosphericconditions from the atmosphere, utilizing said compressed air for theoxidation'of sulphur bearing material to produce a sulphur dioxide gasand then treating said gas toproduce sulphur trioxide. i

2. The improv ent in the process of manufacturing sulphuric anhydrideSin which dried oxygen containing gas is utilized for oxidation of thesulphur material to produce a sulphur dioxide gas which consists incompressing said gas before drying it. I

3. In the manufacture of sulphuric acid, that improvement which consistsin compressing an oxygen-bearing gas, drying the compressed gas bycontact with sulphuric acid, then burning sulphur-containing materialin'contact with such compressed dried gas, and converting the resultingsulphurous A gases into sulphuric acid.

4. In the manufacture of sulphuric acid,

that improvement which consists in compressing an oxygen-bearing gas,drying the compressed gas by contact with sulphuric acid and thenutilizing the resulting gas for the oxidation of elemental sulphur toform sulphuric anhydride.

5. The process which consists in compressing an oxygen-bearing gas,removing impurities from the compressed gas by filtration, then dryingsuch compressed gas by -contact with sulphuric acid,--thereupon burningsulphur-containing material in contact with such compressed dried gas,and converting the resulting sulphurous gases into sulphuric acid.

6. In the manufacture of sulphuric acid, that improvement which consistsin compressing an oxygen-bearing gas, drying said gas by contact withsulphuric acid, utilizing said dried gas for the oxidation of sulphur ofthe Louisiana type to sulphur dioxide and then passing said sulphurdioxide gas, without material lowering of its temperature below theconversion temperature of SO to S0,, in contact with a catalyst for theconversion ofthe SO to S0,.

7 In the'manufacture of sulphuric acid, that improvement which consistsin compressing an oxygen-bearing gas, drying said gas by contact withsulphuric acid, utilizing said dried gas for the oxidation of sulphur ofthe Louisiana type to sulphur dioxide and then passing said sulphurdioxide gas, without material lowering of its temperature below theconversion temperature of SO to S0,, in contact with a platinum type ofgaalyst for the conversion of the S0 to 8. An apparatus for themanufacture of sulphuric acid, comprising a compressor, a drier theinlet of which is connected with the outlet of the compressor, a burnerthe inlet of which is connected with the outlet of the drier, and aplant for converting sulphurous gases into sulphuric acid, the inlet ofsaid plant being connected with the outlet of said burner.

into sulphuric acid, the inlet of said plant being connected with theoutlet of said burner.

10. In the manufacture of sulphuric acid,

that improvement which consists in compressing an oxygen-bearing gas,drying the compressed gas by contact with sulphuric acid, then burningsulphur-containing material in contact with such compressed dried gas,and passing the resulting sulphurous

